Electric switch and contact structure therefor



Jan. 7, 1930. v D Q GARRQWAY 1,742,246

ELECTRIC SWITCH AND CONTACT STRUCTURE THEREFOR Filed Jan. 2, 1926 6; 62 j Flew-w .Zhvei'rfoi',

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Patented Jan. 7, 1930 UNITED STATES PATENT OFFICE DAVID C. .GARROWAY, OF BELMONT, MASSACHUSETTS, ASSIGNOR TO CONDIT ELEC- TRICAL MANUFACTURING CORPORATION, OF SOUTH BOSTON,

CORPORATION" OF MASSACHUSETTS MASSACHUSETTS, A

.ELECTRIC SWITCH AND CONTACT STRUCTURE THEREFOR Application filed January 2, 1926. Serial No. 78,819.

tact member, usually :a rod, ismoved to-complete the circuit. The tube is split along its length to form a plurality of separate segments orshoes, and a coiled annular spring encircles the segments to high against the rod.

hen the switch isopened under heavy press them yieldload it sometimes happens that the circuit-interrupting arc enters the space between two adjacent segments and burns and severs the spring, so that :good pressure contact cannot be made when the switch is again-closed.

It is an objectofth-is'invention to provide Vase mental contact member of the type above set orth with spring-meanszto urge the segments against :the coo'p'eiatingcon'tact rod, the

spring means being so arranged that the circuit-interrupting arc cannot readily gain access thereto.

l V A further-object is the provision of a split 7 contact member so arrangedthat each seg- Inent thereof is independently positively connected electrically in the circuit through the switch.

A further object of the invention is theprovision of a bell-type contact memberandsupporting means therefor :so arranged that the contact member .is self-centering on the co- -'operating contact rod, thereby to facilitate engagement between the two regardless of small departures from absolute alignment.

A further-objectxi's generally'to improve the construction and operation of electric switches and circuit interrupter-s.

I Certain features of this invention are disclosed in my co-pendmg oint application with Chester D. Ainsworth field January 2,

1926,Serial No. 78,818. V

Fig. 1 is 'a more or less diagrammatic representation of the separable contact member of bottom of the recess.

an electric switch in which this invention is incorporated.

Fig. 2 is a side elevation, partly in section, of the stationary contact structure of Fig. 1, in which the invention is embodied.

' Fig. 3 is a plan view of the contact structure of Fig. 2, the supporting bracket being broken away.

Fig. 4 is a section along line 4-4of Fig. 2.

Fig. 5 is a side elevation of one of the segments ofthe bell contact member.

As shown in Fig. 1 the electric switch embodying the invention includes the stationary switch members 10 and the movable switch member 12. The movable switch member includes a cylindrical contact rod 14 which is extendedvertically upward from a supporting bar 16 and is adapted to enter a stationarily-supported tubular contact member or lell 18 carried by a stationary switch mem- The contact bell includes a metal tube which has an internal vertical passage 20 extended from end to end thereof in which the contact rod 14.- is adapted to be received and to make contact. The passage has an out wardly flared lower entrance 22 which facilitates entry of the contact rod into the bell and also serves toeifect the lateral shifting of the bell into alignment with the rod, if the bellis initially displaced from such. alignment. The upper end of said passage is also provided with an outwardly flaring endv24.

. Said bell is supported in a bracket 261which is fixed to and is in electrical connection with a stationary switch member 10. Said bracket is formed or provided with an approximately circular head28 in which said'be'll is received. Said head is formed with a circular recess 30 in its top face and a wall 32 which closes the Said wall is formed with an aperture 34 therein through which the contact bell is extended. A cover plate 36 is disposed on said head to cover the top of said recess and is provided with an aperture 38 through which said bell is extended.

Said cover plate is secured removably in the float therein whereb i to be self-ali nin with 7 E! b the movable contact member. The height of said recess, however, is arranged to be but little greater than the thickness of the flange, so that the bell will be restrained against any material amount of vertical movement.

Said contact bell is slitradially from end to end in a manner to form a plurality of separate segments or shoes 44, three shoes being here shown. Means including spring elements are provided to urge said shoes inwardly toward their common center and said spring elements are arranged to be concealed and shielded against the circuit-interrupting arc. Said means includes a ring 46 which is disposed within said recess 80 and encircles the flange 42 of said contact bell. Said ring is provided with a plurality of radially inwardly directed pins 48 which have screwthreaded outer ends 50 which are screw threaded removably into said ring. are received in radially inwardly directed recesses 52 formed in the shoes a l. As here shown, each shoe is provided with two recesses in which pins are disposed. Springs 54 encircle said pins and are received in enlargements 56 of saidrecesses and are approximately completely'enclosed within said recesses. The inner ends of said springs bear against shoulders 60 of said shoes and theouter ends bear against said ring 46. The arrangement is such that said springsv tends constantly to urge said shoes inwardly toward the common center and thereby into firm contact with the movable contact rod '14 while the pins 48 serve to guide said shoes during such movement. The springs are practically entirely enclosed within the shoes and thereby occupy positions inaccessible to the circuit-interrupting arc. The bottom wall 32 of the recess further shields said springs against contact with the circuit-interrupting arc and the hot gases resulting therefrom.

Said cover plate 36 is provided with an upwardly extended wall 62 which is terminated at its upper end in an inwardly-directed flange 6d whereby to form an enclosure or housing 66 about the upper portion of the contact bell. Means are disposed within said enclosure by which each contact shoe is independently and positively electrically connected with the bracket 26. Said means includes a plurality of flexible loads 68, two

Said pins being associated with each shoe. Said leads are secured to and connected electrically with the shoes by means of screws 70. Slots 72 are formed in the flange 64 and upper portion of the wall 62 of the cover plate adjacent each shoe and the leads are extended in pairs outwardly through said slots. The outer ends of said pairs of leads are reflexed away from each other and against the wall 62, in which position they are secured by screws 74. This arrangement permits the bell to float within its supporting bracket, and permits independent movement of each shoe, while maintaining positive electrical connection between the shoes and the bracket.

I claim:

1. A contact structure for electric switches including a supporting housing open at both ends, and a tubular contact member having a contact-receiving passage extended therethrough which is open at both ends received in and having a floating connection with said housing and extended through both ends thereof for a substantial distance away from said housing both above and below it, whereby the arc is drawn remote from the housing.

2. In an electric switch, a fixed switch terminal, a contact structure therefor including a conducting arm having attaching means at one end connected electrically and mechanically with said terminal and having a housing at the other end provided with an aperture therethrough, and a tubular contact member received loosely in said aperture in angular relation with said arm and extended both above and below said housing and having an outstanding flange which is laterally loose in said housing, and means electrically connecting said contact member and housing loosely.

3. An electric switch having an upper tubular contact member the passage therethrough, being freely openso that arcgases can pass freely upwardly therethrough, a lower contact member comprising a rod movable into and out of the passage in said tubular contact member, said tubular contact member including a plurality of contact segments having resilient supporting means therefor, said resilient supporting means being out of the path of the rising circuit interrupting arc gases through said passage, and means enclosing said resilient supporting means which prevents access of are gases thereto through the spaces between the segments of said contact member.

at. An electric switch having an upper tubular contact member the passage therethrough being freely open so that are gases can pass freely upwardly therethrough, a lower contact member comprising a rod movable into and out of the passage in said tubular contact member, said tubular contact member including a plurality of contact segments, each having resilient supporting means therefor,

each resilient meanscharacterized by lying entirely within the circumferential extent of the segments, and means cooperating with i said segments to shield said resilient supporting means against any deleterious contact with the rising arc gases which may pass through the spaces between aclj acent segments of said contact member.

In testimony whereof, I have signed my name to this specification.

DAVID C. GARROWAY. 

